Process of making cellulose acetate.



which it appertaius to make and use the antral") A earnnr orrrcn.

PHGCEQS 63F iVlAKlNG @ELLLEQQSE ACETATE.

l lo. 826,229.

Specification of Letters Patent.

Patented July 17, 1906.

i u i 5 May 20, 1905.,Serialjlo. 261,420. (Specimens-l To (all whom jitmmy concern: 1 Be it known that l, ARNOLD CoR'rI, a citizen of the Republic of Switzerland, residing in Dubendort, near Zurich, in the Canton of Zurich, Republic of Switzerland, (whose posti ollice address is Diibendorf, .near Zurich,) he *s invented a certain new and useful Process of Making Cellulose Acetate; and I do hereby declare the following to be a full, clear, and exact description of the'invention, such as will enable others skilled in. the art to same.

I have applied for patent in the following countries: in France on August 23, 1904; in Germany on August 24, 1904; in Belgium on April 15, 1905, and in Italy on April 17', 1905.

Heretoiore the manrfacture of cellulose acetates has only been possible by forming first from cotton or cellulose, with the aid of condensation agents, an intermediate product, and then transforming this intermediate product into cellulose acetate, These condensatien agents were either concentrated mineral acids, such as sulfuric acid (a. French Patent N o. 317,007 and Addition No. 1,425) and phosphoric acid (French Patent lie. 316,500) or acetate of zinc or magnesium, (German Patents Nos. 85,329 and 86,368.) Processes are also known according to which the cellulose is first transformed into hydrocellulose, which is then transformed into acetate of cellulose by means of mineral acids, (German Patent No. 118,538, French Patent No. 319,848, United States Patent No.

l have now discovered that cellulose acetates can be made directly by means of cotton or of cellulose almost of the amount theoretically obtainable without the presence of mineral acids if instead of acids dirnethyl sulfate is employed. According to the quantity of dimethyl sulfate used, acetates of different properties may heobtainecl. Thus, for example, one can heat in a bath thirty parts of cotton or ce lulose with seventy parts of acetic-acid anhydrid,one hundred and twenty parts of glacial acetic acid, andthree parts of dimethyl sulfate till dissolution is almost complete. The solution is filtered and the filtrate is poured into a large quantity of water, whereupon the acetate precipitates in a form 1. A process for producing cellulose ace-' tate, which consists in subjecting cellulose to the action of acetic acid, actic-acid anhydrid and dimethyl sulfate, and to heat.

2. A process for producing cellulose acctate, which consists in. subjecting cellulose to the action of acetic acid, acetic-acid auhydrid and dimethyl sulfate.

3. A process for producing cellulose acetate, which consists in subjecting cellulose to the action of a mixture containing dimethyl sulfate, acetic-acid anhydrid and acetic acid, the quantities of acetic-acid anhydrid and acetic acid being in the ratio of severity to one hundred and twenty.

4.. A process for producing cellulose acetate, which consists in subj ectiug cellulose to the action of a mixture containing aceticacid anhydrid, acetic acid and dimethyl sulfate; filtering the solution thus obtained and pouring the filtrate into water, and permitting the acetate to precipitate.

in testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ARNOLD COR'll.

Witnesses: HERMANN HUBER, A. LIEnnRKNEcnr.

corresponding to tetracetate of cellu-,: lose. The product so obtained is soluble in 

